﻿var flexBackground = function() {

    /**
    CONFIGURATION:
    Define the size of our background image
    */
    var bgImageSize = {
        width: 1280,
        height: 960
    };

    /**
    Declare and define variables
    */
    var $window,
$body,
imageID = "expando",
tallClass = 'tall',
wideClass = 'wide',
$bgImage, $wrapper, img, url, imgAR;

    /**
    Are we dealing with ie6?
    */
    var ie6 = ($.browser.msie && parseInt($.browser.version, 10) <= 6);

    /**
    Set up the action that happens on resize
    */
    var resizeAction = function() {
        var win = {
            height: $window.height(),
            width: $window.width()
        };

        // The current aspect ratio of the window
        var winAR = win.width / win.height;

        // Determine if we need to show the image and whether it needs to stretch tall or wide
        if (win.width < bgImageSize.width && win.height < bgImageSize.height) {
            $body
.removeClass(wideClass)
.removeClass(tallClass);
        } else if ((win.w < bgImageSize.width && win.height >= bgImageSize.height) || (winAR < imgAR)) {
            $body
.removeClass(wideClass)
.addClass(tallClass);
            // Center the image
            $bgImage.css('left', Math.min(((win.width - bgImageSize.width) / 2), 0));
        } else if (win.width >= bgImageSize.width) {
            $body
.addClass(wideClass)
.removeClass(tallClass);
            $bgImage.css('left', 0);
        }

        // Need to fix the height of the wrapper for IE6
        if (ie6) {
            $wrapper.css('height', win.height);
        }
    };

    return {

        /*
        Sets up the basic functionality
        */
        initialize: function() {

            // No need for any of this if the screen isn't bigger than the background image
            if (screen.availWidth <= bgImageSize.width || screen.availHeight <= bgImageSize.height) {
                return;
            }

            // Grab elements we'll reference throughout
            $window = $(window);
            $body = $('body');

            // Parse out the URL of the background image and drop out if we don't have one
            url = $body.css('background-image').replace(/^url\(("|')?|("|')?\);?$/g, '') || false;
            if (!url || url === "none" || url === "") {
                return;
            }

            // Get the aspect ratio of the image
            imgAR = bgImageSize.width / bgImageSize.height;

            // Create a new image element
            $bgImage = $('<img />')
.attr('src', url)
.attr('id', imageID);

            // Create a wrapper and append the image to it.
            // The wrapper ensures we don't get scrollbars.
            $wrapper = $('<div></div>')
.css({
    'overflow': 'hidden',
    'width': '100%',
    'height': '100%',
    'z-index': '-1'
})
.append($bgImage)
.appendTo($body);

            // IE6 Doesn't do position: fixed, so let's fake it out.
            // We'll apply a class which gets used in the CSS to emulate position: fixed
            // Otherwise, we'll simply used position: fixed.
            if (ie6) {
                $wrapper.addClass('ie6fixed');
            } else {
                $wrapper.css({
                    'position': 'fixed',
                    'top': 0,
                    'left': 0
                });
            }

            // Set up a resize listener to add/remove classes from the body
            $window.bind('resize', resizeAction);

            // Set it up by triggering a resize
            $window.trigger('resize');
        }
    };
} ();

